Steel-trussed structure



Feb. 23 1926.

J. G. JACKSON STEEL TRUSSED STRUCTURE Filed Feb. 10, 1925 llll I My aliilph.

Illl l l I l l III. giiiii! I II Patented Feb. 23, 192.6.

UNETEE 4S tries.

:STEEL-TRUSSED STRUCTURE.

Application filedFebruary 10, 1925. Serial No. 8,234.

To all commit may cancer-n:

Be 1t known that I, JOHN GRANT JACK- soN, a subject of the King of GreatBritain,

and a resident of the city of Chatham, in thecountyofKent, in .theProvince of Ontario, Canada, have invented certain new and usefulImprovements in Steel-Trussed Structures, of which the following is .thespecification.

My invention relates to improvements in steel trussed structures .andthe object .of the invention is to devisea steel structure stiffened andreinforced bya cementitious material in such a manner as to increase thestrength of the structure under compression strains to be at least equalto the tensile strength of the steel.

A further object is to construct a cement reinforced steel structurewhich will have less tendency to deflect or buckle under compression dueto transverse or bending stresses {as a result-of the greater spacing ofthe active elements and consequently greater moment of inertia of thecross section and at the same time being of such nature as to resistmore effectively such compression strains by virtue of the greater crossseotional area of the compression resisting material.

A still further object is to .devise a cement reinforced steel trussedstructure that can be readily constructed :and which will be 7comparatively light in weight for its size and strength.

Another object is to devise a trussed structure which will lend itselfto being nested during manufacture, transportation and storage, and yetanother object is to devise a structure in which several units can be.built up into a complete trussed structure either during manufacture orerection.

My invention consists of a cement reinforced steel structure constructedand arranged all as hereinafter more particularly described andillustrated in the accompanying drawing in which a Fig. 1 represents afront elevational view of my preferred construction, showing the same inthe form of a pole.

Fig. 2 is a side elevation thereof.

Fig. 3 is a crosssectional View taken on the line 3-3 Figure 1.

Fig. t is an enlarged cross sectional view on the line 4 4i Figurel.

Like characters-of reference indicate corresponding parts in thedifferent views.

'1 are the longitudinal steel members of the structure, eachconsistingpreferably of,

a plurality of spaced apart steel rod members disposed as .is showninthe cross sectional views and of sufficient s'trengthto take care of.the tensile stresses required, when taken together with the relativelysmall longitudinally extending auxiliary steel members 2 whichsurround'the 'members-1 and are adapted to retain the cement filler 3 inposition, it being-understood that the steel members 1 and 2are'embe'dde-din Portland cement or other.cementitiousmaterial of therequisite consistency to reinforce them under compression strains. Theindtependent longitudinal members "1 and the auxiliary members 2 whichpreferably consist of wire mesh and the cement filler 3 are tiedtogether by means of suitably spaced lateral steel members 4, which areembedded or encased in the-lateral cement members 5.

The cement portion of the unit -structure is preferably cast about themembers 1, "2 and 4 so that the .lateral cementmembers 5 will behomogeneously united to thegoement fillers 3.

In the form of pole illustrated, the unit is of substantially V-shapedcross section, being provided with opposed longitudinal flange portions6. Reinforcing cement ribs encasing steel reinforcing and tieing members8 are provided for increasingthe resistance against distortion atthejunction of the-flange members with the legs of the V-shaped portion.7 I

9 are cross straps constructed of-meta'l or cementitious material,either reinforced or not as the case may be, said straps extendingacross the opposite faces of the flanges 6 to the faces provided withthe ribs 7 and adapted .to be secured to such flanges by means ofthebolts 10 which extend therethrough. v

The straps time provided forpreventing the distortion of the legs of thepole due to excessive spreading stresses. The straps 9 are not appliedto the pole until the same is about to be erected, and consequently mypoles, which are of V shaped crosssection, will nest togethervd'uringstor'age or transportatiom as indicated in dotted lines in Figure 3. i

Where desired, two of my poles of V- shaped cross section can be erectedin opposed relation to one another and joined together by lateralmembers, thus making up a much stronger structure. Used singly, they areparticularly applicable for use as trolley or electric light poles.

They are in fact reinforced steel structures in which the reinforcementis cementitious material such as Portland cement. The principle involvedis entirely distinct from reinforced cement structures in which thereinforcing steel is provided for reinforcing the cement against tensilestresses whereas in my structures the cement is provided for reinforcingthe steel against compressive strains, which experience has shown to bethe limiting strain in the design of steel truss poles. or towerstructures.

Itis particularly noticeable by all engineers using steel trussed polesand towers that such structures are relatively weak in the memberssubjected to compressive strains due to the tendency to deform or buckleunder stresses substantially less than tensile stresses which suchmembers resist.

A pole contructed according to my invention overcomes this ditficulty bythe use of a plurality of independent members tied together by suitablydisposed transverse members, each member as above stated comprisinglongitudinally disposed steel members which are provided withcompression reinforcement of cementitious material such as Portlandcement.

The complete pole whether in the case of unit construction or built upform is capable of resisting compressive strains better than a steelstructure of equal steel cross sectional area and further, such a polewill'be substantially. equal in weight to a structure composed solely ofsteel of the same strength and will be much lighter than a reinforcedconcrete pole of the same size and strength. It will moreover lenditself much more readily to being transported due to its light weightand adaptability to nesting, as well as effecting a considerable savingin material and labour in construction. 7

In providing the ribs 7, I do so to increase the resistance of the angleportions to lateral stresses which might tend to spread the flanges 6.This is particularly desirable as a means for resisting the groundpressure upon the outwardly extending flanges 6 in the case of a poleembedded in the'soil and subjected to lateral strains.

On referring to the drawing, it will be noted that the transversemembers 5 are of deep cross section below the ground line of the polesin order to act as ground anchors for, lateral stresses. 1

WVhat I'claim as my invention is 2.

1. 'A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitudinal steel members together, saidlongitudinal and transverse members encased in cementitious material,opposed longitudinal flanges on the sides of the structure, and tieingmeans extending between the opposed flanges.

2. A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitudinal steel members together, saidlongitudinal and transverse members encased in cementitious material,opposed longitudinal flanges on the sides of the structure, andtransverse straps extending between the opposed flanges and securedthereto.

3. A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitudinal steel members together, saidlongitudinal and transverse members encased in cementitious material,opposed longitudinal flanges on the sides of the structure, andreinforcing means between the flanges and main portion of the structurefor reinforcing the junction of the flanges and the main portion againstfracture or distortion.

4. A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitutudinalsteel members together, saidlongitudinal and transverse members encased in cementitious material,opposed longitudinal flanges on the sides of the structure, laterallyextending spaced ribs of cementitious material between the flanges andthe main portion of the structure, and reinforcing and tieing metalmembers in the ribs secured at their ends to the longitudinal steelmembers.

5. A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitudinal steel members together, saidlongitudinal and transverse members encased in cementitious material,and opposed longitudinal flanges on the sides of the struc ture, thestructure being V-shape in cross section for enabling one structure tobe nested within another.

7 6. A cement reinforced steel structure comprising independentlongitudinal steel members, suitably spaced transverse steel membersconnecting the respective longitudinal steel members together, saidlongitu dinal and transverse members encased in cementitious material,and opposed longitudinal flanges on the sides of the structure, thestructure being V-shape in cross section for enabling one structure tobe nested within another, and the main portion of the structure betweentransverse members having orifices extending through the cementitiousmaterial.

7. A cement reinforced steel structure members arranged so that whenencased in comprising independent longitudinal steel the cementitiousmaterial the resultant members, suitably spaced transverse steelstructure Will be V-shape in cross section 10 members connecting therespective l0ngitu-' With orifices extending through the legs of 5 dinalsteel members together, said longituthe structure between the spacedtransverse dinal and transverse members encased in members. cementitiousmaterial, the longitudinal JOHN GRANT JACKSON,

